bad gun anatomy
Tag given to an image featuring a firearm that is drawn such that it is: impossible to be used reasonably (ex: the stock is so long that it prohibits shouldering, lacking a trigger or means to fire, etc), absurd (ex: non-deliberate barrel curvature, abnormally large/small bore or barrel OD for the chambering and vice-versa, barrel/bolt coming out of an optic, etc), resembles a caricature of the firearm it is supposed to be, has overbearing errors (ex: whole cartridges being ejected or shot out, single action firearm going 'click click click', etc ), or just generally looks trash.
This tag should not be used to describe depictions of operator error such as backwards magazines or optics. It should also not be used to describe firearms that have small faults in furniture or continuity (ex: grip slightly too long or at slightly wrong angle, modern handguard on a vietnam-era ar, etc), or are deliberately comically large/small.
If antique firearm is applicable to the gun in question, then design faults should (most likely) be considered part of the style and not bad gun anatomy.